Conventionally, well operation and production involves continuous monitoring of various subsurface formation parameters. Continuous monitoring of parameters such as, for example, reservoir pressure and permeability indicate the formation pressure change over a period of time. It is essential to predict the production capacity and lifetime of a subsurface formation. These parameters have generally been obtained during these operations either through wireline logging, drill stem tests or logging while drilling.
With the increase in the importance of production optimization in order to get more oil from depleted reservoirs, newly drilled wells, deep wells, wells having more complex trajectories and wells that are located in more challenging environments, long term monitoring of wells has become even more desirable. In order to achieve this, it is proposed to locate sensors in the formation, possibly buried some distance in the formation around the borehole outside the casing or tubing in the borehole, or in the formation prior to the installation of the casing or the tubing.
It is an object of the invention to provide a technique that allows sensors to be positioned outside the casing or very deep, such as 100, foot in the formation while still allowing communication without the problems of the previous techniques.
An example of one of these difficulties has been in communicating with the sensor through the casing or tubing and deep below the surface, and in providing electrical power to these sensors. The current invention has the advantage that the sensors are capable of communication through the casing or tubing and at high depths, and that they can be electrically powered.